Integrating color filters into frontlight for reflective display

Abstract

A light guide may include a light guide core, light-extracting elements and cladding layers having lower refractive indices than that of the light guide core. The light guide may be a component of a front light system for a display. The display may be a reflective display, such as a reflective liquid crystal display (LCD). One cladding layer may include color filters for the display and may be disposed between the light guide and the display. The front light system may include a light source system capable of providing light (which may be polarized) to the light guide. The light-extracting elements may be capable of extracting light from the light guide and providing extracted light to the display, via the color filters. The light-extracting elements may include electrodes, such as electrodes for a touch sensor system.

What is claimed is: 
     
         1 . An apparatus capable of providing light to a display, the apparatus including a light guide that comprises:
 a light guide core;   a first cladding layer disposed between the light guide core and the display, the first cladding layer having a lower refractive index than that of the light guide core, the first cladding layer including color filters for the display; and   light-extracting elements capable of extracting light from the light guide and providing extracted light to the display via the color filters.   
     
     
         2 . The apparatus of  claim 1 , wherein the first cladding layer comprises:
 binder material having a lower refractive index than that of the light guide core; and   color filter material in the binder material, the color filter material including at least one of nanoparticles or absorptive dyes.   
     
     
         3 . The apparatus of  claim 1 , wherein the first cladding layer comprises:
 a low refractive index sub-layer; and   a sub-layer of color filters.   
     
     
         4 . The apparatus of  claim 3 , wherein the sub-layer has a refractive index in the range of 1.36 to 1.41. 
     
     
         5 . The apparatus of  claim 1 , further including a light source system capable of providing polarized light to the light guide. 
     
     
         6 . The apparatus of  claim 1 , wherein the light-extracting elements include electrodes. 
     
     
         7 . The apparatus of  claim 6 , wherein at least some of the electrodes are electrodes of a touch sensor system. 
     
     
         8 . The apparatus of  claim 1 , wherein the apparatus includes a reflective display. 
     
     
         9 . The apparatus of  claim 8 , wherein the reflective display includes a liquid crystal layer. 
     
     
         10 . The apparatus of  claim 8 , further including a polarizing element disposed on at least one surface of the light guide. 
     
     
         11 . The apparatus of  claim 10 , wherein the polarizing element is a polarizing layer that is substantially parallel to a plane of the light guide core. 
     
     
         12 . The apparatus of  claim 11 , further including a second cladding layer disposed between the light guide core and the polarizing layer. 
     
     
         13 . The apparatus of  claim 12 , wherein the light extracting elements are disposed on the second cladding layer. 
     
     
         14 . The apparatus of  claim 10 , wherein the polarizing element is disposed between the light guide and a light source of the light source system. 
     
     
         15 . The apparatus of  claim 8 , wherein the reflective display includes an array of display pixels, further including a control system that is capable of processing image data and of controlling the array of display pixels according to the processed image data. 
     
     
         16 . The apparatus of  claim 15 , wherein the control system further comprises:
 a driver circuit capable of sending at least one signal to the array of display pixels;   a controller capable of sending at least a portion of the image data to the driver circuit; and   an image source module capable of sending the image data to the control system, wherein the image source module includes at least one of a memory device, a network interface, a receiver, a transceiver or a transmitter.   
     
     
         17 . The apparatus of  claim 15 , further comprising:
 an input device capable of receiving input data and of communicating the input data to the control system.   
     
     
         18 . A front light system capable of providing light to a display, the front light system comprising:
 a light guide, the light guide including:
 a light guide core; 
 a first cladding layer disposed between the light guide core and the display, the first cladding layer having a lower refractive index than that of the light guide core, the first cladding layer including color filters for the display; and 
 light-extracting means for extracting light from the light guide and providing extracted light to the display via the color filters; and 
   light source means for providing light to the light guide.   
     
     
         19 . The front light system of  claim 18 , wherein the first cladding layer comprises:
 low refractive index material; and   color filter material.   
     
     
         20 . The front light system of  claim 19 , wherein the low refractive index material has a refractive index in the range of 1.36 to 1.41. 
     
     
         21 . The front light system of  claim 18 , wherein the front light system includes means for providing polarized light to the light guide. 
     
     
         22 . The front light system of  claim 18 , wherein the display is a reflective display and wherein the front light system includes means for polarizing light reflected from the reflective display. 
     
     
         23 . The front light system of  claim 18 , wherein the light-extracting means includes electrodes. 
     
     
         24 . The front light system of  claim 23 , wherein at least some of the electrodes are electrodes of a touch sensor system. 
     
     
         25 . An apparatus, comprising:
 a reflective display; and   a front light system capable of providing light to the reflective display, the front light system including:   a light guide, the light guide including:
 a light guide core; 
 a first cladding layer disposed between the light guide core and the display, the first cladding layer having a lower refractive index than that of the light guide core, the first cladding layer including color filters for the display; and 
 light-extracting elements capable of extracting light from the light guide and providing extracted light to the display via the color filters; and 
   a light source system capable of providing light to the light guide.   
     
     
         26 . The apparatus of  claim 25 , wherein the first cladding layer comprises:
 low refractive index material; and   color filter material.   
     
     
         27 . The apparatus of  claim 26 , wherein the low refractive index material has a refractive index in the range of 1.36 to 1.41. 
     
     
         28 . The apparatus of  claim 25 , wherein the front light system includes means for providing polarized light to the reflective display. 
     
     
         29 . The apparatus of  claim 25 , wherein the front light system includes means for polarizing light reflected from the reflective display. 
     
     
         30 . The apparatus of  claim 25 , further including a second cladding layer disposed between the light guide core and the apparatus for polarizing light reflected from the reflective display. 
     
     
         31 . The apparatus of  claim 25 , wherein at least some of the light-extracting elements are capable of functioning as electrodes. 
     
     
         32 . The apparatus of  claim 31 , wherein at least some of the electrodes are electrodes of a touch sensor system. 
     
     
         33 . A method, comprising:
 extracting light from a light guide core; and   providing the extracted light to a display, wherein the providing involves directing the extracted light through color filters in a cladding layer disposed between the light guide core and the display.   
     
     
         34 . The method of  claim 33 , wherein the extracting is performed by light-extracting elements and wherein the method further involves controlling the light-extracting elements to function as electrodes of a touch sensor system. 
     
     
         35 . The method of  claim 33 , further involving providing polarized light to the display. 
     
     
         36 . The method of  claim 33 , wherein the display is a reflective display, the method further involving polarizing light reflected from the reflective display.